1. Field of the Invention
This invention relates to controlling fuel in an internal combustion engine.
2. Prior Art
Various ways of controlling fuel to be injected into an engine are known. For example, it is known to inject fuel so that some fuel is available during each intake cycle of a four-cycle internal combustion engine. Further, it is known to control the amount of fuel injected during each injection so as to control engine performance and engine operating parameters such as the air fuel ratio. When performing such injections, it is desirable to operate within the linear portion of the fuel injector. That is, the portion of the injector curve where there is a linear relationship between the fuel flow delivered by the injector and the pulse width of the current energizing the fuel injector.
It is known that at relatively low fuel flow rates there may be a nonlinearity in the injector fuel flow characteristics. It would be desirable to avoid operating a fuel injector in such a nonlinear region. This may not be possible because the injector is typically required to provide a relatively large range of fuel flow ranging from very small fuel flow at idle to very large fuel flow at wide open throttle. These are some of the problems this invention overcomes.